1. Field of the Invention
The present invention relates to the interworking of a WLAN network and a 3GPP network, and more particularly to QoS control in the interworking of a wireless local area and a 3GPP network.
2. Description of the Related Art
Progress is currently under way in the 3GPP (Third Generation Partnership Project) toward the standardization of specifications for connecting a 3GPP network and a WLAN (Wireless Local Area Network).
When connecting and coordinating the operation of a WLAN network and 3GPP network, appropriate QoS (Quality of Service) control is necessary for providing the user with a service that maintains the desired quality. The result of investigation by the 3GPP into QoS when linking a 3GPP network and a WLAN network is reflected in 3GPP TR 23.836 v.1.0.0 (2005-11): “Third Generation Partnership Project: Technical Specification Group Services and System Aspects: Quality of Service (QoS) and policy aspects of 3GPP-Wireless Local Area Network (WLAN) interworking (Release 7) (hereinbelow referred to as “3GPP TR23.836 v. 1.0.0”).
FIG. 1 shows the configuration of QoS when interworking a 3GPP network and a WLAN network. This configuration is disclosed in FIG. 5.2 of 3GPP TR23.836 v. 1.0.0.
Referring to FIG. 1, when end-to-end service is offered between a WLAN terminal (WLAN UE) and an outside terminal (TE) by way of a 3GPP network, QoS control is carried out in each of bearer (3GPP IP Access Bearer Service) 91 that is established between WLAN UE and a PDG (Packet Data Gateway) and bearer (WLAN Bearer Service) 92 that is established between WLAN UE and WLAN AN (Access Network). The bearer established between WLAN UE and the PDG is hereinbelow referred to as a “3GPP bearer.” The bearer established between WLAN UE and WLAN AN is hereinbelow referred to as a “WLAN bearer.”
It is applied in a 3GPP network that QoS by means of 3GPP traffic classes. QoS according to the IEEE 802.11e standards are applied in the wireless sections of a WLAN network. The settings content and method differ between a system in which QoS is realized by 3GPP traffic classes and a system in which QoS is realized by the IEEE 802.113 standard.
In addition, as the interworking of a 3GPP network and WLAN network, a method has also been prescribed for establishing an IPSec (IP Security) tunnel between the 3GPP network and WLAN terminals. This IPSec tunnel corresponds to 3GPP bearer 91 shown in FIG. 1. Considered from the standpoint of the 3GPP network, a WLAN network is positioned as a transfer path for merely transferring IP packets, and as a result, the 3GPP network takes into account neither the state nor the configuration of the WLAN network in QoS control.
FIG. 2 is a table showing the mapping of 3GPP traffic classes and DSCP (Diffserv Code Point) values conferred to headers of IP packets. This table is disclosed as Table A3 in Annex A of 3GPP TR23.836 v.1.0.0. It is conceivable that the PDG shown in FIG. 1, when encapsulating IP packets to be transmitted to WLAN UE by an IPSec tunnel, determines DSCP values that are conferred to IP headers by means of the mapping table of FIG. 2.
As described above, QoS according to the IEEE 802.11e standard is applied in wireless sections of a WLAN network. The IEEE 802.11e standard prescribes four access categories as packet transmission queues to realize priority control of wireless sections, and further prescribes mapping between access classes and 802.1d tags.
FIG. 3 is a table showing the mapping of access categories and 802.1d tags. This table is prescribed by IEEE 802.11e and is disclosed as Table A1 in Annex A of 3GPP TR 23.836 v.1.0.0. In WLAN AN shown in FIG. 1, the determination of access categories in accordance with the mapping table of FIG. 3 can be considered when transmitting IP packets to WLAN UE by WLAN bearer (WLAN Bearer Service).
However, the above-described art has problems as described below.
When interworking a 3GPP network and WLAN network, QoS control in the 3GPP network and QoS control in the WLAN network are each implemented independently.
When setting an IPSec tunnel, WLAN UE and PDG carry out a QoS negotiation and determine 3GPP traffic classes. At this time, the configuration and state of the WLAN network are not taken into account, as previously described. On the other hand, a WLAN network that only transfers IP packets of an IPSec tunnel does not consider the QoS negotiation results.
Uniform QoS values (access categories) such as “Best Effort” are therefore set for all users in the WLAN network, and QoS control is carried out based on these settings. Consequently, QoS control appropriate to actual services such as VoIP and streaming is not implemented, thereby raising the danger of drops in quality of service caused by delay or data loss.
It has therefore not been possible to implement appropriate QoS control in the wireless sections of the WLAN network when interworking a 3GPP network and WLAN network.